From:	carlosad AT yahoo DOT com (Carlos Albar-Diaz)
Subject:	Re: DLL help needed
14 Nov 1998 06:08:35 -0800 :
Message-ID:	<19981114105740.21077.qmail.cygnus.gnu-win32@findmail.com>
References:	<3646EB36 DOT 35E244A9 AT uniweb DOT se>
To:	gnu-win32 AT cygnus DOT com

I have failed in my attempt to modify Mumit's "dllhelpers" package to 
create dlls  from WINAPI/__stdcall functions.  It works all right when 
the function inputs/outputs are integers, but it fails when I try to
 use floats or doubles.

I have browsed all the relevant archives and I have seen similar problems
reported, but no solutions.

Any ideas? I will appreciate them very much.

BTW, I am using egcs1.1 for mingw32.

Thanks, Carlos
PS: Thanks Jens for your comments, now I attach all the files for your enjoyment :)

This is the (failed) output of the program usedll.c, attached below:
-----------------
dll_double_square (3.0) = -1.#IND00  ---> calcs the square of a double
                                         (fails with WINAPI convention)
dll_int_square (30,40) = 1200        ---> multiplies 2 ints, works OK
------------------

When I get rid of the WINAPI attributes, everything works well. The
problem I have is that I have to use WINAPI to call the DLL from 
MS Excel.

All the sources and make commands follow:
-------------------
make commands
-------------------
gcc -c -DBUILDING_DLL=1 -I. -g -Wall  -o cdll.o cdll.c
gcc -c -DBUILDING_DLL=1 -I. -g -Wall  -o dllinit.o dllinit.c
dlltool --export-all --output-def cdll.def cdll.o dllinit.o
dllwrap --def cdll.def --driver-name gcc -o cdll.dll \
    cdll.o dllinit.o  
gcc -c -I. -g -Wall  -o usedll.o usedll.c
dlltool --dllname cdll.dll --def cdll.def \
    --output-lib libcdll.a
gcc -o usedll.exe -g -Wall   usedll.o -L./ -lcdll

C:\usr\dll\c>


------------------------
cdll.c
-------------------------
#include "cdll.h"
DLLIMPORT WINAPI int 
dll_int_square (int i, int j)
{
  return i * j;
}
DLLIMPORT WINAPI double 
dll_double_square (double d)
{
  return d * d;
}
------------------------
cdll.h
-------------------------
#include "windows.h"  //CAD inserted this
#ifndef cdll_h_included
#define cdll_h_included
#if BUILDING_DLL
# if __GNUC__ && ! defined(__declspec)
#  define DLLIMPORT
#  define DECLSPEC_NOT_SUPPORTED
# else /* ! __GNUC__ || __declspec */
#  define DLLIMPORT __declspec (dllexport)
# endif /* ! __GNUC__ || __declspec */
#else /* Not BUILDING_DLL */
# if __GNUC__ && ! defined(__declspec)
#  define DLLIMPORT extern
#  define DECLSPEC_NOT_SUPPORTED
# else /* ! __GNUC__ ||  __declspec) */
#  define DLLIMPORT __declspec (dllimport)
# endif /* ! __GNUC__ ||  __declspec) */
#endif /* Not BUILDING_DLL */


DLLIMPORT WINAPI int dll_int_square (int, int) ;
DLLIMPORT WINAPI double dll_double_square (double);

#ifndef DECLSPEC_NOT_SUPPORTED
#else /* DECLSPEC_NOT_SUPPORTED */
#define dll_global_int_var (*_imp__dll_global_int_var)
#endif /* DECLSPEC_NOT_SUPPORTED */
#endif /* cdll_h_included */
------------------------
usedll.c
-------------------------
#include <stdio.h>
#include "cdll.h"
int main () { 
  printf ("dll_double_square (3.0) = %f\n", dll_double_square (3.0));
  printf ("dll_int_square (30,40) = %d\n", dll_int_square (30,40));
  return 0;
}
-----------------------------
cdll.def (generated automatically, same for the import library and the dll)
-----------------------------
; dlltool --export-all --output-def cdll.def cdll.o dllinit.o
EXPORTS
	dll_int_square AT 8 @ 1 ; 
	dll_double_square AT 8 @ 2 ; 
-----------------------------
dllinit.c
-----------------------------
/* dllinit.c -- Portable DLL initialization. 
   Copyright (C) 1998 Free Software Foundation, Inc.
   Contributed by Mumit Khan (khan AT xraylith DOT wisc DOT edu).
 */

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#undef WIN32_LEAN_AND_MEAN
#include <stdio.h>

BOOL APIENTRY DllMain (HINSTANCE hInst, DWORD reason, 
                       LPVOID reserved /* Not used. */ );

#ifdef __CYGWIN32__

#include <cygwin32/cygwin_dll.h>
DECLARE_CYGWIN_DLL( DllMain );
/* save hInstance from DllMain */
HINSTANCE __hDllInstance_base;

#endif /* __CYGWIN32__ */

BOOL APIENTRY
DllMain (
	 HINSTANCE hInst /* Library instance handle. */ ,
	 DWORD reason /* Reason this function is being called. */ ,
	 LPVOID reserved /* Not used. */ )
{

#ifdef __CYGWIN32__
  __hDllInstance_base = hInst;
#endif /* __CYGWIN32__ */

  switch (reason)
    {
    case DLL_PROCESS_ATTACH:
      break;
    case DLL_PROCESS_DETACH:
      break;
    case DLL_THREAD_ATTACH:
      break;
    case DLL_THREAD_DETACH:
      break;
    }
  return TRUE;
}


>  What exactly is the problem? Do you get any error messages? How does
> the names look in the .dll? Have you exported the functions? I'm not
> sure the __stdcall does that. I guess you link a .def file with the .dll
> to export the functions. Have you looked att the site for mingw32???
> 
>  Jens Yllman
> 


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